Catalyst-Free Carbon Dioxide Conversion in Water Facilitated by Pulse Discharges
Tianqi Zhang, Josip Knežević, Mengying Zhu, Jungmi Hong, Rusen Zhou, Qiang Song, Luyao Ding, Jing Sun, Dingxin Liu, Kostya Ostrikov, Renwu Zhou, Patrick J. Cullen
Abstract
By inducing CO 2 -pulsed discharges within microchannel bubbles and regulating thus-forming plasma microbubbles, we observe high-performance, catalyst-free coformation of hydrogen peroxide (H 2 O 2 ) and oxalate directly from CO 2 and water. With isotope-labeled C 18 O 2 as the feedstock, peaks of H 2 18 O 16 O and H 2 16 O 2 observed by ex situ surface-enhanced Raman spectra indicate that single-atom oxygen (O) from CO 2 dissociations and H 2 O-derived OH radicals both contribute to H 2 O 2 formation. The global plasma chemistry modeling suggests that high-density, energy-intense electron supply enables high-density CO 2 – (aq) and HCO 2 – (aq) formation and their subsequent coupling to produce oxalate. The enhanced solvation of CO 2, facilitated by the efficient transport of C x O y ionic species and CO, is demonstrated as a crucial benefit of spark discharges interacting with water at the bubble interface. We expect this plasma microbubble approach to provide a novel power-to-chemical avenue to convert CO 2 into valuable H 2 O 2 and oxalic acid platform chemicals, thus leveraging renewable energy resources.